Thank you so much for your reply.
----- Original Message ----- > From: Nick Holland <n...@holland-consulting.net> > Sent: Monday, September 19, 2011 8:13 PM > Subject: Re: Disabling PIO / LBA48 on large drives , Blade 150 > See the commit message for pciide.c: > Changes since revision 1.321: +15 -1 lines > > Revision 0xc4 and earlier of the Acer Labs M5229 UDMA IDE controller > can't do DMA for LBA48 commands. Work around this issue by > (silently) falling back to PIO for LBA48 commands. Access to the > tail end of large disks will be much slower, but at least it works. You know, I feel silly. I went to the effort of grabbing the 4.9 kernel sources and trying to read through them to figure out how the whole LBA48 on Acer M5229 situation was getting handled, etc. Admittedly a little dangerous, not having done disk I/O drivers for anything other than DOS, and that too a while back. I was looking for a more "obvious" comment like the one in FreeBSD's ATA code, and not finding it, I wasn't as rigorous as I should have been in trying to understand what the code was actually doing. After seeing the commit message via cvsweb and actually looking at __wdstart(), I now see what's going on. > how's that for the best of all worlds (all things considering)? > Have ALL your disk, and have all the available performance, too! > Put your frequently used stuff in the 0-128G space, and your > less-used stuff in the 128G+ space. No recompiling, no kernel > hacking, no jumpers on disks. Yeah, I think that's called having your cake and eating it too :) (again, all things considered). Thanks once again for saving me from needlessly wasting my time, wringing my hands, and all other forms of unnecessary effort and energy by pointing this out. Best regards.
